Crytsal glazing - two challenges - the glazes are very fluid at the right temperature and tend to run - wax the bottoms of your pieces and use a lot of kiln wash or things are going to get stuck in the kiln. Second problem is that you need very careful temperature control to nucleate and grow nice crystals. A little too low or a little high and it doesn't give good results and the target temperature changes with the glaze composition. That said some of the most beautiful pieces I have ever seen were done with some striking crystal glazes. There is one that is kind of a bronze color with blue crystals that I really like but haven't been able to find a composition for so we haven't tried to make it.